The Houthi rebels escalation in the Yemeni province of Marib is “concerning” because it undermines peace prospects aimed at ending the war, the UN envoy to the country said on Tuesday.
The Iran-backed rebels have been pushing on several fronts towards the last government-controlled major city in the north that hosts millions of displaced people.
Heavy fighting is taking place along its frontlines, including its borders with Al Jawf, Sanaa and Bayda governorates.
“The political importance of Marib must also not be underestimated," Martin Griffiths said during a Security Council briefing.
"Military shifts in Marib will have ripple effects on conflict dynamics.
“If Marib falls, this would undermine prospects of convening an inclusive political process that brings about a transition based on partnership and plurality."
The northern city has become a safe haven for thousands of displaced people from around the country.
“Nowhere is the importance of this choice more evident than in Marib," Mr Griffiths said.
"The situation in Marib is concerning in a number of ways. High level of loss of lives. A real threat to hundreds of thousands of internally displaced people and people in need."
He warned that Yemen would slip back away from the road to peace.
“Alas, this is exactly what seems to be happening. Increased fighting, greater humanitarian needs and the Covid-19 pandemic is still taking its toll,” Mr Griffiths said.
He said delegations from the warring parties were set to meet on Thursday in Switzerland to discuss the UN-backed agreement on prisoner releases.
The two sides, which had been meeting in Jordan, are expected to convene for week-long talks to finalise a deal on prisoner releases.
They committed to release “conflict-related prisoners and detainees back in 2018 in Stockholm, and furthered their discussions to fulfil this commitment in Amman earlier this year”, Mr Griffiths said.
He said he was deeply concerned about fuel shortages in Houthi-held areas, which could result in dire humanitarian consequences.
“I want to emphasise the importance of ensuring that civilians can regularly access adequate supplies of fuel and other essential goods," Mr Griffiths said.
"The flow of essential commercial imports, including food, fuel and medical supplies, and their distribution throughout Yemen to civilians must be ensured."
The Houthis took over Sanaa and most northern cities in 2014 after forcing out the internationally recognised government of President Abdrabu Mansur Hadi.
The fallout from the conflict has led the UN to describe Yemen as one of the world’s most desperate humanitarian disasters.
Mr Griffiths has been pushing both sides to agree on a process to end the war but lack of trust from both sides has stalled his efforts.
The United Kingdom's representative to the UN, Jonathan Allen, urged the two sides to quickly agree to a ceasefire and engage in a comprehensive political process.
Mr Allen said if they will not make any moves towards peace then the Security Council will take action.
"A political solution is needed desperately to alleviate the humanitarian crisis and end the conflict for good. The window of opportunity to end this conflict will close," he said.
Mr Alllen said the warring parties must work with Mr Griffiths to reach an agreement.
"It is in their hands whether they are ready to act in the interests of their people or only in their own self-interest," he said.